1. Field of the Invention
The present invention relates generally to well head pumping units and in particular to a pumping unit with a constrained bridle strap.
2. Description of the Prior Art
Well head pumping units are placed over wells for operating down-hole pumps whereby oil, water, etc. are extracted and brought to the earth's surface. The Pauls U.S. Pat. No. 4,631,970 discloses a pumping unit with a bridle strap connecting the drive system thereof with a rod string. The flexible bridle strap transfers the reciprocating motion of the pumping unit drive system to a vertically reciprocating motion of the rod string. However, the equalizer beam which connects the drive system to the bridle strap assembly in this pumping unit is unconstrained. Thus, the equalizer beam can damage other components of the pumping unit if tension is released, e.g., if the rod string breaks. The pumping unit shown in the aforementioned Pauls '970 patent is designed to equally divide the rotation of the drive system between the upstroke and downstroke of the rod string, i.e. 180.degree./180.degree.. However, in many applications different upstroke/downstroke ratios are preferred. For example, relatively high viscosity oil and/or slant hole applications often necessitate a slower downstroke in order to maintain tension on the bridle strap assembly.
The present invention addresses the shortcomings of the prior art. Heretofore there has not been available a slant hole pumping unit with the advantages and features of the present invention.